We hypothesize that coordinated surface behavior, such as swarming motility and biofilm formation, is crucial for competitive success in diverse environments. We propose to examine the details of these complex surface behaviors in a model system, Variovorax paradoxus. Based on previous work in our lab, we have demonstrated the presence of a wetting agent that is produced during swarming. We will identify this wetting agent and the genes involved in producing the material. Based on previous work on V. paradoxus biofilms, we have identified a type IV pilus locus as well as numerous genes involved in lipopolysaccharide and exopolysaccharides that influence swarming and biofilm phenotypes. We will further examine the roles of the pilY1 gene, which has been implicated in several aspects of surface behavior, and which may be present in several isoforms. Our preliminary data shows that independent insertion mutants in this gene can have divergent phenotypes, consistent with the hypothesis that two protein isoforms are playing different roles in these behaviors. The genes of the LPS/eps synthesis loci will be investigated and their roles synthesis of surface and secreted polysaccharides will be determined using genetic and biochemical tools. We will examine the culture conditions that control the decision between these surface behaviors, and identify mutants that are defective in swarming motility, focusing on the signal transduction pathways that trigger the response. These experiments will allow us to build a model of V. paradoxus surface behaviors that includes the structural components critical to motility and sessile development, as well as the signal transduction pathways and biochemical circuits that control this decision. PUBLIC HEALTH RELEVANCE: Bacterial success in many environments is dependent on coordinated surface behaviors, including motility and sessile development as a biofilm. In this study, we examine the surface behaviors and associated structures -- such as wetting agents, pili, flagella, and exopolysaccharides-- of the soil bacterium Variovorax paradoxus, the genes involved in these behaviors and their regulation by environmental cues. These studies will result in a comprehensive model of these surface behaviors, which are crucial to bacterial survival in many environments, with particular relevance to opportunistic infections and virulence.